The side grill provides 2 options for the typical psu with a fan - either use the PSU fan to help remove air from the case or isolate the PSU from the warm air in the case by using the side grill to draw air into the PSU.

The distinct top (open) & bottom (more or less closed) of the SS-400FL create a different situation and the likely preference may depend on the air flow of the case.

My htpc uses 3 fans, none of which are front fans. The vga fan (attached to an accelero) blows air over the top of the video card and directly onto the cpu hs/fan.

A pic of the layout with air flow arrows:

The optimal position of the PSU would seem to be to have the top (with the holes) facing inward since the air flow of the case would pull air in from the outside through the PSU if given an opportunity. In addition to some air flow, you get the added benefit of diminishing exposure to any PSU hum (however slight). I don't believe isolating the PSU from the case (by reversing the position such that the holes face the side grill) would benefit the PSU (although it might make the case a tad cooler but I wouldn't expect by much) and it would only create another opening for hum (however slight) to leak outside the side of the case.

Given the preference for some external means of airflow for fanless PSU's, it's hard to imagine any everyday scenario in which isolating the PSU from the inside of the case by using the external case grill would be advantageous.

The comment about going up to 700W with a fan is interesting. Makes me wonder why they don't release a version with a fan that only kicks in above 400W. With one of the 5000 series Radeons and a modern 6 core CPU you could have a system that runs fanless in normal use but can ramp up to heavy processing or games easily.

Was wondering the same thing. There would be significant demand for that type of PSU. There are plenty of people with setups that utilize very little draw most of the time (using word, browsing, etc.) but who prefer the comfort of knowing they can draw load or upgrade components (adding sli/crossfire, etc.) without concern for the PSU.

I think for most purposes the x-650 probably meets this need (non-gaming = silent; gaming equals a very quiet fan). However, what's wrong with asking for a little more wiggle room (ie. silence up to 400w instead of 150w, and a little more power on the upper end)? Under those conditions, most could actually game with silence and have little concern with adding SLI, etc. Of course, most can comfortably game under silence with the SS-400FL but one still faces the possibility of needing to replace the unit should they add a 2nd vga.

I have an early quad core Intel CPU (one of the rather warm 65nm ones) and a 4870. Actually it's a crappy nVidia 680i based board which doesn't help matters. My system can pull 450W at the wall in some games.

At work I built a system for a client with 5870 and AMD hex core CPU on an Intel mobo with 4GB RAM. Idles at about 90W with no tweaking.

The optimal position of the PSU would seem to be to have the top (with the holes) facing inward since the air flow of the case would pull air in from the outside through the PSU if given an opportunity. In addition to some air flow, you get the added benefit of diminishing exposure to any PSU hum (however slight). I don't believe isolating the PSU from the case (by reversing the position such that the holes face the side grill) would benefit the PSU (although it might make the case a tad cooler but I wouldn't expect by much) and it would only create another opening for hum (however slight) to leak outside the side of the case.

Given the preference for some external means of airflow for fanless PSU's, it's hard to imagine any everyday scenario in which isolating the PSU from the inside of the case by using the external case grill would be advantageous.

Any other thoughts?

Personally, my instinct would be to start the other way... But here's the cool part -- which ever way you start with, you can easily try the other way -- just unplug all the cables from the PSU and flip, then replug.

Well, considering the price, i don't see a point of buying this vs the X-650. Take a look - US$139, that is $165 with 19% VAT (the typical VAT in Europe), converted to â‚¬ it is 128 euros. Add a profit for the seller to that and we are at 135-140â‚¬ range. Seasonic X-650 is 130â‚¬. So unless you hate to have a fan in your case, there is no point buying this vs X-650 for typical use.

Even in USA the pricing is same - X-650 on Newegg is $139.99 vs suggested price in the article for X-400, which is $139.

You realize you posted this same complaint on hardocp also. This is rehashing the same thing that Paul Johnson said to you. This is for people who WANT a fanless psu. Not for you obviously. The point of this is EXACTLY FOR PEOPLE WHO HATE TO HAVE A PSU FAN.

I should note I have no interest in a fanless psu either, but I can definitely see the purpose of one. You should be celebrating a great psu instead.

Yes of course merlin. Problem for me is to understand the "want" part of it . In meantime i found one use where it does make a point to have a fanless PSU - in recording studio, or in a place where you have a completely fanless open setup. But once you have a fan on a graphics card, a fan on CPU cooler, a outtake + intake fan - which is a typical setup - the reason for fanless PSU goes away, except for the "good feeling" that "i have a fanless PSU" - because the real difference in noise will be impossible to measure.

So yes, it's mostly for people who want a fanless PSU, without any serious reason.

For example look at allwinner's setup - 9.2cm fan on video card, 9.2cm fan on CPU heatsink, 8cm outtake fan. This is exactly the setup where this PSU doesn't make any sense to use. Those fans will generate a lot more noise than the PSU fan in Seasonic X models with fan up to 400W. And now considering that setup will probably use up to 300W max, the PSU fan will kick in only when you will go over the load where your video card and CPU fan heatsink are already at noisy level.
If he would have a fanless video card, a Scythe Ninja 2 running passive and one 12-14cm fan running at very low speed, i say ok - that is a real use for this PSU. But then you get back to the basic problem, and that in this way you are able to cool only loads where X-650 is running passive too. The difference between X-400 and X-650 is in 200-400W range, and this is the range where i just can't imagine the load which would make PSU fan noise irrelevant.

I just want to know what is the measurable reasons for "want". If the only reason is a "good feeling", then yes, this product is not for me.

So if moving the conversion from 12 volts to lower voltage (5v/3.3) a few inches closer to the outputs is such a big win (diagram page 3 of review). Why not go whole hog and move most of the low voltage conversion the extra 600mm down next to the ATX socket.

i.e. why not make the PSU basically a 400W AC to DC brick (which could still be in ATX PSU form), and provide something like a higher powered, enclosed Pico/Winmate DD-24AX converter near the motherboard.

One could use two low-voltage converters (one in the main PSU to power the drive connectors), or have the drive connectors come from the secondary box, or run the drive power backwards to the main PSU from the secondary box (longer runs - but lower amperage)).

I had a similar reaction as SPCR did in their summary. Originally I was thinking that this was a nice bit of engineering, but would rather have a fan just in case. This review has changed my mind, too.

frostedflakes wrote:

Kind of OT, but Mike, would you happen to know if Seasonic has any plans to release an 80Plus Gold SFX power supply in the near future?

I was about to ask the same thing! Though I'd be happy with any 80 Plus rated SFX from Seasonic. As far as i know they simply don't have anything in this form factor. The only reasonably powered SFX I'm aware of is the 450W Silverstone. I've been looking to build a mITX gaming rig, and am disappointed that everyone uses full ATX PSUs in such builds.

So yes, it's mostly for people who want a fanless PSU, without any serious reason.

For example look at allwinner's setup - 9.2cm fan on video card, 9.2cm fan on CPU heatsink, 8cm outtake fan. This is exactly the setup where this PSU doesn't make any sense to use. Those fans will generate a lot more noise than the PSU fan in Seasonic X models with fan up to 400W. And now considering that setup will probably use up to 300W max, the PSU fan will kick in only when you will go over the load where your video card and CPU fan heatsink are already at noisy level.If he would have a fanless video card, a Scythe Ninja 2 running passive and one 12-14cm fan running at very low speed, i say ok - that is a real use for this PSU. But then you get back to the basic problem, and that in this way you are able to cool only loads where X-650 is running passive too. The difference between X-400 and X-650 is in 200-400W range, and this is the range where i just can't imagine the load which would make PSU fan noise irrelevant.

After analysis of the options, I don't think the issue is as clear cut as you suggest.

My htpc uses an nForce 750 chipset, an Athlon x2 3800 65w, an Nvidia 8800gt video card, and an OCZ 60gb Vertex SSD. The PSU is a Seasonic S12-500 500w PSU. At the time of purchase (2006), it was highly regarded both for its build quality as well as its quietness. It's still highly respected and you'll still see posts referring to this PSU but it's hard to compare how loud it is to current PSU's b/c the testing methodology may have changed (perhaps Mike can comment). Here is the SPCR review of the unit.

It is hard to discern which of the fans is the loudest. The 3 fans are all low-rotation fans that are controlled to spin near their lowest rpm. You have to be within 2-3 feet with no ambient noise to hear anything (I sit about 15 ft. from it). However, it appears the audible noise radiating from the case is not fan noise but rather very mild vibrational noise that seems to eminate from the PSU.

In a low-rpm fan environment reducing the number of fans most always assists in reducing noise/vibration. Thus, I disagree that this is the type of setup where a fanless PSU doesn't make any sense to use. Does it add a significant benefit that justifies the cost? That depends on the purchaser and the particular factors.

Would flipping the PSU such that the intake fan is facing inside the case essentially eliminate the noise from the PSU fan? Perhaps, but not if the noise is actually slight vibrational noise. OTOH, depending on the sensitivity of the fan controller, it could result in increasing the fan speed due to increased temps (unlikely given the airflow in the case but....).

Would a newer PSU with a fan that is quieter be functionally equivalent given that I do have 3 fans (no matter how quiet)? Perhaps. But that again raises questions of value. Let's look at the options.

In terms of cost savings, I could go with the Nexus Value 430 (listed as the 2nd quietest PSU in the review). In fact, this is about the only option that provides significant cost benefits. I would spend $89 (not cheap by any means), lose modular cabling, have a less efficient PSU, a warranty of 2 years (vs. 5 on the Seasonic) and still have to deal with the uncertainties of a fan, which include, among others: (1) Over time, fans typically get louder; (2) Fans are not too infrequently defective and get loud quickly; (3) Inconsistency - my experience with PSU fan noise levels even among well-recognized brands is that they're inconsistent at best. All of these create risks that I have to pay to return the item and deal with additional headaches of reinstalling, etc. I'd rather spend the $135, gain 3 years of warranty and not have the headache of dealing with fan related issues. Of course, having a fanless PSU removes the difficulty of trying to optimize fan levels b/c you have one less fan which may or may not be giving off noise or contributing to vibration.

Other options, gleened from page 6 of the review listing PSU's with the lowest sound signature, are even less attractive.
(1) ENERMAX MODU82+ 625w PSU. Alas, it's less efficient at the draw the htpc is running, has a 3 year warranty and is the same price as the fanelss. Plenty of reports of loud fans. Guess that's out of the equation. What may, or may not, be the 500w non-modular equivalent currenctly goes for $100 ($80 after MIR at the moment). Alas, not modular, 3 year warranty but it does come with the ever fun and exciting game of "fan roulette." No thanks. Enermax Modu 82+ 425W? About $120 shipped if you can find it - not as quiet as the Nexus Value but it is modular.
(2) Seasonic M12D 850W. Even more expensive and less efficient at low draw.
(3) Antec CP-850. At $105, it's cheapar but still has a fan that's always on and is less efficient at the loads operated. This PSU is not a standard design and can only be used with certain cases (iirc, 3, maybe 4, cases). This rules out the majority (including htpc use).
(4) Coolermaster M700W. $110-15 shipped....not much savings and certainly not silent. Besides, I went through 3 Cooler Master "silent" or "quiet" PSU's in search of "quiet" to no avail (admittedly I haven't used the line in question but Coolermaster lost me as a customer with what was obviously deceptive marketing with the units I had).
(5) Nexus RX-6300. Untested but comes recommended on the forums. Alas, $130 & still has a fan.

Given the value comparison of these other units, I disagree with you that this fanless unit does not bring a competitive value to this niche market. In fact, only the Nexus Value can compete and it does so poorly above 200watts (arguably not my htpc during standard operations).

This evaluation merely emphasises the primary question to be answered that we've seen over and over (in this short time period of these products existence): To buy the x-400, x-650 or the x-750. After all, the 650 is actually cheaper at the moment, provides headroom for higher demanding rigs and is essentially fanless for low power draw usage (such as an htpc or when using the PC for day to day tasks). I haven't come to a firm opinion. There are a lot of factors to consider (ie., future proofing, swapping opportunities, resale, efficiency disparity, etc.). I'd like to see a version with a fan that remains off until 350-400w and is spec'd to 800-850. Ultimately, neither the 650 or 750 provide safe headroom for absolute silence except in conservative usage. According to the SPCR 650 review (p.3, bottom chart), the "hybrid silent fan control" keeps the fan off up to 20% +-5. The range of power draw to maintain silence for the x-650 is 97.5 to 162.50 (with spec at 130w), while it is 112.5 to 187.50 (spec at 150) for the x-750. Any gaming or encoding load on a mid-range PC/htpc may bring the fan to life (althogh they're clearly very quiet at low draws). Thus, these aren't a real substitute for the x-400 (and that doesn't take into account the greater cost of the x-750).

It'll be interesting to see what the fanless 460w offers. Given the close power rating to the 400, it seems to be unnecessary. Offer 1 or the other but if a PC is really pushing for that extra 60w, then it probably needs a different PSU altogehter. Or, convert that 460w to a hybrid fan control 350/750w and we'll all be happy.

Note: The 80mm rear fan in the diagram is in the wrong position - it's actually on the rear-inner spot while the rear-outer spot fan is off). Fanless might be possible on this htpc but would probably be pushing it, particularly when gaming (which I don't do frequently on the htpc but will every rare once in awhile).

Ultimately, before purchasing this unit, I would disconnect all of the fans to better ascertain just how much noise the PSU is really giving off. I did that in the past to optimze the # of fans as well as fan speed but I don't recall the results vis a vis the PSU.

Last edited by allwinner on Tue Aug 31, 2010 7:25 pm, edited 1 time in total.

Was wondering the same thing. There would be significant demand for that type of PSU. There are plenty of people with setups that utilize very little draw most of the time (using word, browsing, etc.) but who prefer the comfort of knowing they can draw load or upgrade components (adding sli/crossfire, etc.) without concern for the PSU.

They basically do have that type of PSU. The X650/750. The only difference is likely the slightly beefier heatsinks. My 750 is generally fanless well past 250W. I would be surprised if there were any real material differences between the 650 and the 400 except for the vented case and larger heatsinks. With the fan going, the vented case would likely result in the fan needing to spin faster due to worse forced cooling pathways.

Well, considering the price, i don't see a point of buying this vs the X-650. Take a look - US$139, that is $165 with 19% VAT (the typical VAT in Europe), converted to â‚¬ it is 128 euros. Add a profit for the seller to that and we are at 135-140â‚¬ range. Seasonic X-650 is 130â‚¬. So unless you hate to have a fan in your case, there is no point buying this vs X-650 for typical use.

Even in USA the pricing is same - X-650 on Newegg is $139.99 vs suggested price in the article for X-400, which is $139.

You realize that the x-650 has an MSRP of 179.99 right? Its likely that the 400 will be cheaper at retail once supplies stabilize than the 650. Probably in the $90-120 range.

Yes of course merlin. Problem for me is to understand the "want" part of it . In meantime i found one use where it does make a point to have a fanless PSU - in recording studio, or in a place where you have a completely fanless open setup. But once you have a fan on a graphics card, a fan on CPU cooler, a outtake + intake fan - which is a typical setup - the reason for fanless PSU goes away, except for the "good feeling" that "i have a fanless PSU" - because the real difference in noise will be impossible to measure.

@aaronspink: Do you realize that with 5750, you will have hard time getting it ower 200W ? Actually, a i7 920 + GA-EX58-UD5 + 6GB RAM + Velociraptor WD3000GLFS + 5750 (not a green version, a standard one) has ~195W maximal load from socket according to a review (and if Gigabyte Odin PSU doesn't lie, then it was 155W when not counting the PSU efficiency). Now, that is 155W. Seasonic X-650 and X-750 will run fanless in that case.
The MSRP... Well, that is all nice, but pretty much pointless if no one sells at that price. And here in Europe we don't have anything called MSRP, no one publishes it.

Kind of OT, but Mike, would you happen to know if Seasonic has any plans to release an 80Plus Gold SFX power supply in the near future? If it wouldn't be too much trouble, maybe you could inquire to one of the reps you normally speak with. I contacted Seasonic about a month or two ago about this, but never received a reply. The SS-300SFD in my NSK-3300 is getting a bit long in the tooth, and I was thinking about how nice it would be to replace it with an 80Plus Gold unit, especially if they can build an SFX unit that has similar noise characteristics to the ATX form factor X Series PSUs. Unfortunately I don't think I have the room to fit an RM112 or anything like that in the top compartment, it's just too long.

Hi, this is something we have been working on but not easy to achieve due to the low power output and the 12V to 3.3 & 5V ratio. To get our 400w to Gold was already a big step. Maybe next year...

Hi All,
Quick intro, I'm the Seasonic Rep and from time to time I will visit the forum and try to answer some open issues. As I do not visit the forums often, if there are urgent questions/requests, please send PM.

Anyway, a big THANK YOU to everyone for all the great support and Mike, thanks for the great review!

Hi, this is something we have been working on but not easy to achieve due to the low power output and the 12V to 3.3 & 5V ratio. To get our 400w to Gold was already a big step. Maybe next year...

Good to hear that this is being worked on, I've traditionally been put off by SFX due to the lack of quality components available.

Mike would it be possible for you to use this in a 'traditional' top mounted PSU tower? I'm quite keen to know how it would perform with such restricted ventilation (so would quite a few other Solo owners I would imagine!). Although given the torture test I'm fairly sure it will survive!

Mike would it be possible for you to use this in a 'traditional' top mounted PSU tower? I'm quite keen to know how it would perform with such restricted ventilation (so would quite a few other Solo owners I would imagine!). Although given the torture test I'm fairly sure it will survive!

Already answered similar question above -- I think it'll work fine. An aluminum case would have some small advantage -- better heat transfer from the rising heat to the al. panel to the outside air.

The comment about going up to 700W with a fan is interesting. Makes me wonder why they don't release a version with a fan that only kicks in above 400W. With one of the 5000 series Radeons and a modern 6 core CPU you could have a system that runs fanless in normal use but can ramp up to heavy processing or games easily.

Seasonic is a company that "gets it" and is making products for quietness enthusiasts. So why is it still necessary for us to void our warranties and smother coils in liquid electrical tape ourselves to eliminate coil whine? It's not difficult or expensive - they should do it at the factory.

Kind of OT, but Mike, would you happen to know if Seasonic has any plans to release an 80Plus Gold SFX power supply in the near future? If it wouldn't be too much trouble, maybe you could inquire to one of the reps you normally speak with. I contacted Seasonic about a month or two ago about this, but never received a reply. The SS-300SFD in my NSK-3300 is getting a bit long in the tooth, and I was thinking about how nice it would be to replace it with an 80Plus Gold unit, especially if they can build an SFX unit that has similar noise characteristics to the ATX form factor X Series PSUs. Unfortunately I don't think I have the room to fit an RM112 or anything like that in the top compartment, it's just too long.

Hi, this is something we have been working on but not easy to achieve due to the low power output and the 12V to 3.3 & 5V ratio. To get our 400w to Gold was already a big step. Maybe next year...

Thanks for taking the time to register and reply, nice to know that this is a product you guys have considered. I figure there's probably not a huge demand for SFX units (at least not in retail, OEM might be a different story), so I wasn't sure. Will see if I can get another year or so of use out of my SS-300SFD, and hopefully a new SFX model will be available sometime in 2011. If not I'll probably just replace it with the same thing, the SS-300SFD has served me well for the last four years or so.

Kind of OT, but Mike, would you happen to know if Seasonic has any plans to release an 80Plus Gold SFX power supply in the near future? If it wouldn't be too much trouble, maybe you could inquire to one of the reps you normally speak with. I contacted Seasonic about a month or two ago about this, but never received a reply. The SS-300SFD in my NSK-3300 is getting a bit long in the tooth, and I was thinking about how nice it would be to replace it with an 80Plus Gold unit, especially if they can build an SFX unit that has similar noise characteristics to the ATX form factor X Series PSUs. Unfortunately I don't think I have the room to fit an RM112 or anything like that in the top compartment, it's just too long.

Hi, this is something we have been working on but not easy to achieve due to the low power output and the 12V to 3.3 & 5V ratio. To get our 400w to Gold was already a big step. Maybe next year...

Thanks for taking the time to register and reply, nice to know that this is a product you guys have considered. I figure there's probably not a huge demand for SFX units (at least not in retail, OEM might be a different story), so I wasn't sure. Will see if I can get another year or so of use out of my SS-300SFD, and hopefully a new SFX model will be available sometime in 2011. If not I'll probably just replace it with the same thing, the SS-300SFD has served me well for the last four years or so.

Hi frostedflakes,
Glad to hear your 300SFD is still serving you well.

You are correct in saying the SFX is mainly for OEM and in this market, mostly 80PLUS Bronze will suffice. That said, low power units with Gold certification does have its markets, ie., servers & IPC but so long as it has multi-outputs, it is a challenge.

Difficult to say, as an earlier post pointed out; 5 years ago, we would not have imagined 90%+ efficiency from a standard ATX.

seasonic, my favorite brand of all time. My old 300w super tornado is stull running in my file server after being used in my workstation for some time. It is probibly a good 7 years old now, having only needed to replace the fan. My current one is a corsair HX520 (seasonic made) which i purchased shortly before seasonic made there own modular PSU's (ohwell). And it has also had exceptional performance for everything i can throw at it. I know it will survive through many upgrade's and last me for years.

Cudo's to you guys for being one of the few company's around that strives to be the best and build a reputation on quality rather then marketing.

You are correct in saying the SFX is mainly for OEM and in this market, mostly 80PLUS Bronze will suffice. That said, low power units with Gold certification does have its markets, ie., servers & IPC but so long as it has multi-outputs, it is a challenge.

Difficult to say, as an earlier post pointed out; 5 years ago, we would not have imagined 90%+ efficiency from a standard ATX.

Gold is nice, but the SFX market is so empty that even 80 Plus bronze parts would be a step up. As you say, it's mostly spartan OEM PSUs in this market, with only the Silverstone ST45SF targeting the gaming SFF group. For all the enthusiasts building mITX gaming rigs in Sugo cases, all you have to do is pass up the ST45SF to hae a home run.

I can't explain Seasonic's rationale but the 460W model does include an extra PCIe power cable if you don't mind paying a bit extra (no idea how much extra).

The other alternative is to avoid nVidia until they do a die shrink and hopefully get they're house in order. However given the reputation of the 200 series I'm not exactly optimistic.

First of all, 460GTX does not require 8-pin connectors - just regular 6-pin ones. Second, since its already in the market, why would you want a different card, say, the 2xx series? Or a 470?

Lastly, why can't you use the ever popular 2 molex > 6-pin cable?

On the other hand, I'm positive there eventually will be a "green" GTX460 with a single 6-pin and lower clocks. The regular one barely exceeds 150W under heaviest load anyway.
And there will obviously be cards like 455 and 450 that will give you similar performance and will have a single 6-pin power connector.

As a side note, AFAIR there are v few 400 watter (and lower) with double PCI-E connectors - one I remember is Enermax Liberty. And you are right - there should definitely be more 400W PSUs with dual VGA power cables...
_____

As to the reviewed PSU - I was reading it with a blissfully stupid grin, drooling and in awe. My wife asked "what's this? why so happy?". Didn't answer, she wouldn't understand...

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